Alka-Seltzer is a popular antacid and pain reliever that has been around since 1931. It is a combination of aspirin, citric acid, and sodium bicarbonate. Bromo-Seltzer is a similar product that was introduced in 1888 and contains bromide instead of aspirin. Carbonated water, also known as seltzer, is a type of water that has been infused with carbon dioxide gas, giving it a bubbly texture. All three of these products are used to treat indigestion, heartburn, and other stomach ailments.